1. Field of the Invention
The present invention relates to a signal display lamp that includes a display portion capable of performing display in a plurality of colors.
2. Background Art
Patent Literature 1 discloses a level meter that has a basic structure as a signal display lamp. This level meter includes a plurality of light sources that are arranged in a line in an up-down direction, a plurality of globes with which the plurality of light sources are respectively covered, and a lighting control circuit that turns on/off each of the plurality of light sources. A plurality of luminous divisions are formed by respectively combining the light sources and the globes together. An output signal of a liquid quantity sensor that detects the quantity of liquid in a water tank is input to a programmable controller, and the programmable controller converts the output signal of the liquid quantity sensor into BCD (binary-coded decimal) data. The BCD data is input to the lighting control circuit. The lighting control circuit selects a luminous division that is to emit light based on the BCD data, and allows a light source of the luminous division selected thereby to be lit. Accordingly, a level display corresponding to the output of the liquid quantity sensor is performed. It is possible to perform an alarm display according to a liquid quantity level, for example, by color-coding such that, in order from the bottom side, a globe having a predetermined number of luminous divisions is set in green, and a globe having a predetermined number of luminous divisions above the green globe is set in yellow, and a globe having a predetermined number of luminous divisions above the yellow globe is set in red.
One Prior Art Document is Patent Literature 1: Japanese Patent Application Publication No. 4-309818.